--------------------------------------------------------------------------------

A Summary of The 27th General Meeting of the ILC Physics Subgroup

Sep. 8, 2012 (Sat) at Room 425, Building 3, KEK

--------------------------------------------------------------------------------

0) Attendants:

Present at KEK:

T.Horiguchi (Tohoku)

A.Ishikawa (Tohoku)

J.Tian (KEK)

C.Calancha (KEK)

R.Yonamine (Sokendai)

Y.Okada (KEK)

M.Nojiri (KEK)

T.Uchiyama (KEK)

K.Fujii (KEK)

T.Tanabe (Tokyo)

T.Suehara (Tokyo)

H.Ono (NDU)

S.Kanemura (Toyama)

T.Nabeshima (Toyama)

K.Tsumura (Nagoya)

T.Yamashita (Aichi Med.)

Via video conf.

K.Kotera (Shinshu)

------------------------------------

Opening Comments

------------------------------------

1) ZH analysis: main decay modes (H.Ono)

Status:

- BR studies (bb, cc, gg)

- arXiv:1207.0300v1 --> to be submitted to EPJ

- Input to DBD physics chapter

- Update mh to 125GeV.

- Use LHC HDECAY-based BRs instead of Pythia-based ones.

- 1TeV analyses

- Extrapolation from 120GeV to 125GeV: (250fb^-1@250GeV)

delta (sigmaxBR)/(sigmaxBR)

----------------

1.0% -> 1.1 (bb)

7.6% -> 8.5 (cc)

6.7% -> 7.2 (gg)

8.4% -> 7.2 (WW)

----------------

- Invisible BR

BR=1.1% @ 95CL

5sigma observation @ BR=2.8%

Next Step:

- 1TeV analysis for LCWS12 (priority).

- Publication of H->bb,cc,gg: very soon.

- H->WW*, ZZ*

2) Measurements of tan(beta) in 2HDMs (K.Tsumura)

- Introduction:

Softly Z2 broken 2HDM --> 5 degrees of freedom left

* m^2_H,A,H+/- ~ M^2 + lambda v^2/2

* sin(beta-alpha) <-> VVH

* tan(beta) = v2/v1

- LHC data suggests sin(beta-alpha) ~ 1

- FCNC -> 4 types if extra Z2 parity is imposed.

- Type-II

g_Hbb ~ m_b tan(beta) sin(beta-alpha)

g_Htt ~ m_t cot(beta) sin(beta-alpha)

- LHC's H search

production: bbH followed by H->tau tau

-> small mA large tan(beta) region has been excluded.

- ILC

sigma(HA) pronto tan^2(beta) -> not useful considering LHC limit

BR(H/A->bb) loses sensitivity to tan(beta) if tan(beta)>>1 since (H->bb becomes almost 100%)

Gamma_H,A propto tan^2(beta) -> not useful considering LHC limit

--> Not very much room left for ILC.

- Type-X

No strong constraint from LHC as compared to the Type-II case.

- ILC

tau tau for this type

BR, Gamma_H,A also useful since the allowed parameter space is much wider.

- Future direction

Other types.

3) ZH analysis: rare modes, H->AA (C.Calancha)

Status:

- Z->H->gamma gamma @ Ecm=250GeV

sigma*BR(H->AA) = 320fb * 0.3% = 0.9fb --> 240 ev

BG: qqaa or qqaa: 2000 times larger than the signal

Z->ll,qq, nunu

- Full simulation study (w/ LOI samples)

- Preselection

2 isolated neutral (photon-like) PFOs (ecalE/(ecalE+hcalE), E/p)

90 < maa < 150GeV

Z->qq selection

72 < mjj < 102.5GeV

Npfo > 30

pt_h > 35GeV

cos(theta_a-h) < 0.85

Z->nunu selection

pt_h > 35GeV

cos(theta_a-h) < 0.85

- Count the number of events in the mass window: (115,125) (mh=120GeV)

--> delta (sigma x BR) / sigma x BR = 35%

Next step:

- Use cos(theta_Z) and and cos(theta_j) in Z decay.

- h->mu mu @ 1TeV before (h->Za)

4) ZH analysis: H->tau+tau- (S.Kawada)

Status:

- Z->H->tau+tau- @ Ecm=250GeV 250fb^-1, P(e+,e-)=(+0.3,-0.8)

- Full simulation study (w/ LOI samples)

1st step: (Z->ll)

delta (sigma x BR) / (sigma x BR) = 16% (w/o requiring isolation for leptons)

Next step:

- Improve isolated lepton selection

- Improve jet clustering for taus

- Cut optimization

- Z->qq

- Results by LCWS12

5) Inflation and DM in a radiative seesaw model (T.ZNabeshima)

gauge symmetry breaking

- Introduction:

Omega_0 = 1.002 +/- 0.011 --> Omega_p - 1 < )(10^-6) but why? : flatness problem

Horizon problem: CMB anisotropy

--> Inflation

Is Higgs inflation possible

--> xi = 5 x 10^4 sqrt(lambda) can satisfy the slow-roll condition.

--> but there are two problems:

unitarity -> E cannot reach M_p --> new extra heavy particle

Vacuum stability broken at O(10^10) GeV --> extended Higgs

--> Inert doublet model

--> mh=126, mH+/-=138.5, mH=150, mA=65GeV

- Questions/Comments

- How can we make sure that this is really related to inflation?

--> parameter values are constrained rather strictly to allow inflation.

6) ZHH (Junping Tian)

Status:

- New weighting method:

dsigma(x)/dx = B(x) + lambda I(x) + lambda*2 S(x)

--> Found a general solution for weighting function:

w_0(x) = const x (I(x)+2S(x))/sigma(x)

--> delta lambda/lambda = 1.8 x delta sigma /sigma

--> 1.66 x delta sigma / sigma --> 7-8% improvement at 500 GeV (ZHH)

--> delta lambda/lambda = 0.85 x delta sigma /sigma

--> 0.76 x delta sigma / sigma --> 11% improvement

at 1000 GeV (nnHH)

- nunuHH at 1TeV with new fast sim sample with modern flavor tagging TMVA analysis resulted in much better separation of signal from BG.

--> delta lambda / lambda = 16% w/o nnZH and ttH BG (2ab^-1)

--> delta lambda / lambda ~ 20% if these BGs are included

- Global analysis for Higgs coupling determinations

--> Relative errors on

hzz: 1.25%

hww: 1.35%

hbb: 1.94%

hcc: 2.53%

hgg: 2.79%

htautau: 2.54%

haa: 6.80%

Gamma_tot: 5.96%

Next Step:

- 120 -> 125GeV

- Theorists should start thinking about how to improve theoretical ambiguities due to QCD loop corrections and mb, etc.

7) Higgs phenomenology of the SUSY-GUT broken by the Hosotani mechanism (T.Yamashita)

- Ref: PRD84, 115016 (2011)

- Outline:

SGGHU (Supersymmetric grand gauge-Higgs unification)

--> doublet-triplet (DT) splitting problem naturally solved

- SGGHU:

Hosotani mechanism

vev of zero mode of A5 breaks symmetry.

A5 is massless at tree level (since it is from gauge field)

--> A5 aquires a mass of O(mSB) via loop. -> 1TeV (if SUSY)

--> Light adjoints: Sigma_1, Sigma_2, Sigma_3

--> These adjoint matters disturb gauge coupling unification.

--> Addition of extra vector-like matter fields can recover the unification.

--> QCD is no longer asymptotic free!

--> squarks and octet become rather heavy.

--> colorless fields may be still light.

--> 126GeV Higgs is OK in this model.

- Effective SGGHU theory

Singlet (S) and Triplet (Delta)

--> no 4-point self coupling (gauge coupling)

--> 3-point self coupling from gauge coupling

lambda_Delta = 2 sqrt(5/3) lambda_S = g_1,2,3 @ GUT scale.

Lambda_Delta=1.1 lambda_S=0.26

--> Testable deviations (a few %) from SM or MSSM.

- Comments:

What about investigate the allowed mass range for colorless particles after the 14TeV LHC runs.

8) TT Subgroup (T.Horiguchi)

Status:

- Reviewing threshold physics.

Threshold scan, AFB, top momentum distribution

- Generated 20k signal events with physic, processed with Mokka and Marlin

- Reading analysis code for ZHH and TTH.

Next Step:

- Top reconstruction by next week.

- WW BG study in 4 weeks.

- Top Yukawa measurements in 6 weeks.

----------------------------------------------------------

The slides shown at the meeting is available from

http://ilcphys.kek.jp/meeting/physics/

see them for details.

---------------------------------------------------------

------------------------------------

Discussions on future direction and mile stones

------------------------------------

*) Meeting Schedule:

LCWS2012 Meeting: Oct 22-26, Arlington, Texas.

Next general meeting (2012/10/13 10:30) : Conf.ID: 713

*) Talks to be submitted to LCWS2012

Experiment:

Higgs BR (main mode, …): Ono

Higgs BR (rare mode: AA, mumu): Tino

Higgs BR (tau tau): Kawada

Self-coupling: Junping/Suehara

TTH: Tanabe/(Tony?)

Theory:

K.Tsumura: tan(beta)

T.Nabeshima: Higgs inflation and ILC

K.Yagyu: Triplet Higgs and ILC

M.Kakisaki: ILC and GUT with Hosotani mech.

M.Aoki: ILC and Majorana nu in radiative seesaw

T.Shindou: Extended SUSY, EW-baryogenesis, and ILC

T.Yamada: Strongly coupled SUSY and ILC

H.Sugiyama: Radiative seesaw with spontaneous breaking of (B-L)-gauge symmetry and ILC

Y.Kikuta: Composite Higgs and ILC?

Working group web page:

http://www-jlc.kek.jp/subg/physics/ilcphys/

Slides are available from http://ilcphys.kek.jp/meeting/physics/